The program objective of this interdisciplinary dentistry-engineering study is to increase the service life of amalgam restorations. Current work on extracted teeth has shown that the predominant cause of failure is galvanic corrosion which degrades and embrittles the amalgam. The process can be duplicated, in vitro, as a screening test for modified alloys and modified alloys and manipulative techniques. A critical part of the galvanic circuit is the electrolytic transport of Sn into the dentin. The mechanisms which determine setting expansion have been identified and control can be imposed over the basic Ag3 Sn composition. Commercial alloys usually contain copper as a minor alloying element. Its presence is essential for stable shelf life but it modifies phase behavior and heat treatment response. Electronic instrumentation for measurement or oral potential patterns shows promise as a diagnostic tool, in clinic, to detect incipient failure. Three clinical problems will be undertaken: 1) Retardation of galvanic degradation by blocking of ten migration with cavity sealants by refining the microstructure to reduce gamma 2 interconnection and by optimizing the phase distribution of Cu. 2) Developing technique for replacing lost tooth structure by amalgam and securing metallurgical bond to an adjacent restoration. This will require null expansion amalgams to minimize interface stresses and re-activation of structurally degraded restorations. 3) Correlation of oral potential patterns with clinical observations to establish techniques and interpretation as a routine diagnostic tool.